1. Field of the Invention
The present invention relates to an image capture apparatus, control method thereof, and recording medium and, more particularly, to a dynamic range extending technique which extends a tone range by compositing a plurality of differently exposed images.
2. Description of the Related Art
In recent years, some image capture apparatuses such as digital cameras and digital video cameras have a dynamic range extending function which obtains an image whose tone range is extended by compositing a plurality of differently exposed images, which are obtained by capturing images of a subject using different exposure times.
Japanese Patent Laid-Open No. 2008-104009 discloses an image capture apparatus which generates an HDR image by capturing two different images, which respectively fall within luminance ranges on a high-luminance side and low-luminance side by detecting a highest luminance on the high-luminance side and a lowest luminance on the low-luminance side when a captured image does not fall within a predetermined luminance range.
Also, a technique for dynamically controlling image composition in dynamic range-extended image generation processing (to be referred to as HDR image generation processing hereinafter) so as to avoid image discontinuity in a composite image output by the HDR image generation processing when a moving object is included has been disclosed.
Japanese Patent Laid-Open No. 2002-101347 discloses the following technique. That is, when an HDR image is generated using two images, that is, an underexposed image and overexposed image, a region where image discontinuity may occur is specified based on differences between tone levels of normalized images, and replacement to the underexposed image is inhibited in that region.
However, even when the aforementioned method of Japanese Patent Laid-Open No. 2002-101347 is used, pixels extracted from both the overexposed image and underexposed image may often be used in a moving object region of the HDR image generated by composition, thus posing a problem of texture discontinuity in the moving object region.